Background: Abnormalities in the number of vessels can be found for both the umbilical artery and vein. We sometimes encounter cases of a decreased number of umbilical cord vessels, such as a single umbilical artery. In contrast, there may be an increase from three to four vessels within the umbilical cord. A supernumerary umbilical vein is particularly very rare, and it is generally found in combination with congenital anomalies. We report a case of a partial supernumerary umbilical vein.
Case presentation: The previous pregnancy of a 37-year-old healthy Japanese woman (gravida 2, para 1) had been uncomplicated, and the resulting child was alive and well. Prenatal examination at 36 weeks of gestation revealed the coexistence of a four-vessel part and a normal three-vessel part of the umbilical cord. A healthy female neonate weighing 2726 g was born at 38 weeks of gestation. The umbilical cord measured 40 cm in length; the four-vessel part continued to a distance of 18 cm from the surface of the infant's body, and the remaining umbilical cord comprised three vessels. On histological examination, the fetal side of the umbilical cord had two arteries and two veins, and the placental side had two arteries and one vein. Isolated supernumerary umbilical veins tend to be overlooked. We consider that it is important to evaluate the number of umbilical cord vessels in the second trimester using ultrasound combined with color Doppler in at least three sites: the insertion sites on both the fetal abdomen and placenta, and the free loop of the umbilical cord.
Conclusions: Prenatal diagnosis of isolated supernumerary umbilical cord vessels tends to be overlooked. However, supernumerary vessels of the umbilical can be associated with fetal congenital anomalies. The number of vessels within the umbilical cord must be examined because the detection of such abnormalities may lead to the prenatal diagnosis of other congenital anomalies.
Keywords: Case report; Congenital anomaly; Four-vessel umbilical cord; Prenatal diagnosis; Single umbilical artery; Supernumerary umbilical vein.